The microprocessor industry continues to scale down the feature sizes and the number of transistors on VLSI circuits. Scaling below the 100 nm node has produced the situation in which SEM inspection no longer offers suitable resolution to image key artifacts and structures. Therefore, the transmission electron microscope (TEM) is considered to be the method of choice for process control and failure analysis, especially for measurements such as the thickness of non-planar barrier and seed layers. However TEM samples must be thin in order for the high energy electrons to transmit through the samples and image the sample. To prepare such specimens, focused ion beam (FIB) microscope is used to cut a biopsy specimen from the silicon wafer and thin it to be used for TEM imaging and evaluation. After the specimen is cut by FIB, a nanomanipulator is used for “in-situ lift-out” to lift the specimens and put it on the TEM grid for imaging. For that, a sharp probe (mainly a tungsten probe) is brought in contact with the specimen using a nanomanipulator arm. Then, using ion-beam metal deposition, the tungsten probe is welded to the specimen, and the specimen lift and move by the manipulator and placed on the TEM grid. Then, using the FIB, the tungsten probe is cut and separated from the specimen.
However, after each cut, the probe tip become thicker (due to conical shape of the tungsten probe), and finally the user must either sharpen it using the FIB or eventually change the probe when sharpening takes very long time.
As just another challenge in failure analysis of devices in semiconductor industry, currently there are methods for modifying circuits after they are insulated by oxide coatings or similar materials. The circuit can be edited and/or redesigned by forming secondary connections on top of the insulating layer. Currently the FIB is used to first open vias (i.e. hole) in the silicon oxide layer and reach to the metal contact underneath. Then, metal (e.g. tungsten) is deposited using ion-beam metal deposition to fill the vias with metal. Finally the metal is deposited between the two vias to connect the two points together. However the metal deposition rate between the two vias is usually a slow process and takes several minutes to deposit a few micrometer-long contacts.